"The slime was kind of gooey and a little gross," he said. "Sometimes there would be these dummy aliens that had nobody in them and then there would be the actual guy in the alien suit who was very skinny. And so you didn't know if it was a dummy or a real guy. Sometimes they'd be sitting on the chair and all the sudden they'd jerk and move and you'd be like, 'Oh my god, there's a guy in there."

Ben's wife Christine Taylor walked the red carpet as did Kendra WilkinsonBaskett, who popped by for the event.